1. Field of the Invention
The present invention relates to an improvement in an exhaust gas reflux apparatus for an internal combustion engine that refluxes an exhaust gas into a combustion chamber to inhibit an excessive increase in combustion temperature of air-fuel mixture and to reduce NOx concentration in the exhaust gas.
2. Description of the Related Art
A known exhaust gas reflux apparatus for an internal combustion engine is, as disclosed in Japanese Utility Model Laid-Open No. 55-137245, such that an exhaust gas reflux valve is provided between a combustion chamber and an exhaust port, the exhaust gas reflux valve is opened in an interlocked manner with an intake rocker arm that is driven to open an intake valve, depending on operation conditions of the internal combustion engine, and an appropriate amount of exhaust gas is sucked into the combustion chamber from the exhaust port during an intake stroke.
Such a construction of the exhaust gas reflux apparatus for an internal combustion engine has a problem in output performance of the engine, since a cylinder head requires a specific exhaust gas reflux valve besides an intake valve and an exhaust valve generally used, and the exhaust gas reflux valve prevents provision of sufficiently large opening areas of an intake port and an exhaust port opening into a limited ceiling surface area of the combustion chamber.